Rotary head and magnetic recording/reproducing apparatus

ABSTRACT

The present invention provides a rotary head comprising a tubular rotary cylinder; and a magnetic head for carrying out at least one of recording and reading of information with respect to a magnetic tape transported about the rotary cylinder; wherein the magnetic head is supported so as to be movable toward the outside of the rotary cylinder.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotary head used for recordingor reproducing information on a magnetic tape, and a magneticrecording/reproducing apparatus equipped therewith.

[0003] 2. Related Background Art

[0004] Magnetic recording/reproducing apparatus such as data storages,audio decks, video decks, and video cameras, which use magnetic tapes astheir recording media, employ rotary heads adapted to helical scanningin order to achieve a higher recording density. Such a rotary head hasconventionally utilized an inductive magnetic head employable for bothrecording and reading information on a magnetic head, or amagnetoresistive head (hereinafter also referred to as “MR head”) whichcan read out information with a sensitivity higher than that of theinductive magnetic head.

[0005] In the inductive magnetic head, the magnetic tape is transportedso as to slide over the magnetic head in order to prevent foreignmatters from attaching to the sliding surface between the tape and headand thereby deteriorating recording and reproducing performances. Thefriction upon sliding wears the magnetic head surface to some extent,whereby a surface without foreign matters is always exposed.

SUMMARY OF THE INVENTION

[0006] However, the following problems may exist in the above-mentionedconventional technique. Namely, while the conventional rotary headtransports the magnetic tape so as to make it slide over the inductivemagnetic head in order to eliminate foreign matters as mentioned above,the magnetic head may break due to unintentional forces received fromthe magnetic tape or the electrostatic discharge (ESD) or thermalasperity (TA) occurring upon contact with the magnetic tape or wear dueto the frictional force accompanying the sliding if the magnetic tape isbrought into too much contact with the magnetic head. If the distancebetween the magnetic tape and magnetic head is too long, on the otherhand, the magnetic head may fluctuate its output or lower itsreproduction sensitivity.

[0007] An example of rotary heads using an MR head is described inJapanese Patent Application Laid-Open No. HEI 11-259834. While theabove-mentioned publication discloses a technique for restraining the MRhead from wearing, there remains plenty of scope for improvement.

[0008] It is an object of the present invention to provide a rotary headwhich can appropriately adjust the contact state between a magnetic headand a magnetic tape, and a magnetic recording/reproducing apparatusequipped therewith.

[0009] The present invention provides a rotary head comprising a tubularrotary cylinder; and a magnetic head for carrying out at least one ofrecording and reading of information with respect to a magnetic tapetransported about the rotary cylinder; wherein the magnetic head issupported so as to be movable toward the outside of the rotary cylinder.

[0010] Since the magnetic head is supported so as to be movable towardthe outside of the rotary cylinder, the rotary head in accordance withthis aspect of the present invention can appropriately adjust thecontact state between the magnetic head and magnetic tape.

[0011] Preferably, the magnetic head is swingably supported by an armdisposed within the rotary cylinder. Providing an arm swingablysupporting the magnetic head as such can easily move the magnetic headtoward the outside of the rotary cylinder.

[0012] Preferably, the magnetic head is disposed on one end side of thearm, and moves to the outside of the rotary cylinder when an airflowcaused by a rotation of the rotary cylinder acts on the other end sideof the arm. When an airflow is generated by a rotation of the rotarycylinder in such a configuration, the magnetic head moves toward theoutside of the rotary cylinder due to the airflow. As a consequence, aconfiguration which can move the magnetic head toward the outside of therotary cylinder can be realized simply at a low cost.

[0013] Preferably, the rotary cylinder is provided with an opening,disposed at a position ahead of the magnetic head in the rotatingdirection of the rotary cylinder, for introducing the airflow therein.In such a configuration, the airflow generated by the rotation of therotary cylinder can reliably be introduced into the rotary cylinder, soas to act on the other end side of the arm.

[0014] The present invention provides a rotary head comprising a tubularrotary cylinder; a magnetic head for carrying out at least one ofrecording and reading of information with respect to a magnetic tapetransported about the rotary cylinder; and gap adjusting means foradjusting a gap between the magnetic head and magnetic tape by using anairflow generated between the magnetic head and magnetic tape.

[0015] Since the gap adjusting means adjusts the gap between themagnetic head and magnetic tape, the rotary head in accordance with thisaspect of the present invention can appropriately regulate the contactstate between the magnetic head and magnetic tape.

[0016] Preferably, the gap adjusting means includes a groove formed in asupport for attaching the magnetic head thereto at a surface opposed tothe magnetic tape, and generates a positive pressure between themagnetic tape and the surface opposed to the magnetic tape. Such aconfiguration can regulate the contact state between the magnetic headand magnetic tape in a direction in which the magnetic tape moves awayfrom the magnetic head.

[0017] Preferably, the gap adjusting means includes a groove formed in asupport for attaching the magnetic head thereto at a surface opposed tothe magnetic tape, and generates a negative pressure between themagnetic tape and the surface opposed to the magnetic tape. Such aconfiguration can regulate the contact state between the magnetic headand magnetic tape in a direction in which the magnetic tape approachesthe magnetic head.

[0018] Preferably, in each of the above-mentioned rotary heads, themagnetic head includes a magnetoresistive device for reading informationof the magnetic tape by using a magnetoresistive effect. A magnetic headutilizing a magnetoresistive device is advantageous in that itssensitivity is higher than that of an inductive magnetic head. However,like the inductive magnetic head, it will be unfavorable if the surfaceof the magnetic head utilizing the magnetoresistive device is worn byfriction with the magnetic tape. In particular, when themagnetoresistive device is worn, the depth (so-called MR height) of thedevice from its surface opposed to the magnetic tape changes, therebyaltering a characteristic of the magnetic head. When the magnetic headand magnetic tape are separated from each other, on the other hand, theoutput sensitivity may decrease greatly, thereby deteriorating theoutput characteristic. Therefore, as mentioned above, the magnetic headis made movable toward the outside of the rotary cylinder, or the gapbetween the magnetic head and magnetic tape is made adjustable by theairflow generated between the magnetic head and magnetic tape, so as toregulate the contact state between the magnetic head and magnetic tapeappropriately, whereby the magnetoresistive device can be prevented fromreceiving too much shock from or friction with the magnetic tape, andthe magnetic head can be kept from deteriorating its outputcharacteristic.

[0019] Preferably, the magnetic head is an inductive magnetic head.Though the inductive magnetic head is supposed to have a surface to beworn by friction with a magnetic tape in general in such aconfiguration, the magnetic head is made movable toward the outside ofthe rotary cylinder, or the gap between the magnetic head and magnetictape is made adjustable by the airflow generated between the magnetichead and magnetic tape, so as to regulate the contact state between themagnetic head and magnetic tape, whereby the magnetic head can beprevented from receiving too much shock from or friction with themagnetic tape and can be kept from deteriorating its outputcharacteristic.

[0020] In another aspect, the present invention provides a rotary headcomprising a tubular rotary cylinder; and a magnetic head for carryingout at least one of recording and reading of information with respect toa magnetic tape transported about the rotary cylinder; wherein themagnetic head is supported so as to be movable toward the inside of therotary cylinder.

[0021] Even when a force directed to the rotary cylinder is applied tothe magnetic tape in the rotary head in accordance with this aspect ofthe present invention, the magnetic head is moved toward the inside ofthe rotary cylinder, i.e., away from the magnetic tape, whereby thecontact state between the magnetic head and magnetic tape can beadjusted appropriately. As a consequence, the magnetic head can beprevented from receiving too much shock from or friction with themagnetic tape.

[0022] The rotary head in accordance with this aspect of the presentinvention may be configured such that the magnetic head is moved towardthe inside of the rotary cylinder due to a pressure from the magnetictape.

[0023] When the magnetic head receives too much shock from the magnetictape in such a configuration, the magnetic head can retract into therotary cylinder, so as to alleviate the impact force, thereby preventingthe magnetic head from being damaged.

[0024] The rotary head in accordance with this aspect of the presentinvention may be configured such that the magnetic head moves toward theinside of the rotary cylinder due to an airflow generated between themagnetic head and magnetic tape.

[0025] When an airflow is generated due to the transportation of themagnetic tape and a rotation of the rotary cylinder in such aconfiguration, the airflow lowers the contact force between the magnetichead and magnetic tape, which can prevent the magnetic head from beingdamaged.

[0026] Preferably, in the rotary head in accordance with this aspect ofthe present invention, the magnetic head is swingably supported by anarm disposed within the rotary cylinder.

[0027] Providing an arm swingably supporting the magnetic head as suchcan easily move the magnetic head toward the inside of the rotarycylinder. If such an arm is flexible, it can swing the magnetic head ina simple configuration.

[0028] In such a configuration, the rotary cylinder may be formed withan opening, whereas at least apart of the magnetic head may project fromthe opening to a periphery of the rotary cylinder.

[0029] The rotary head equipped with the above-mentioned arm may beconfigured such that the magnetic head is attached to a predeterminedsupport, a surface opposed to the magnetic tape in the support isprovided with a head projection controller using a piezoelectricmaterial, and the magnetic head is moved toward the inside of the rotarycylinder by the head projection controller.

[0030] When the piezoelectric material of the head projection controlleris displaced so as to deflect the support, the magnetic head can easilybe moved toward the inside of the rotary cylinder. In this case, thesurface opposed to the magnetic tape in the support may be provided withthe head projection controller.

[0031] The rotary head equipped with the above-mentioned arm may beconfigured such that the magnetic head is attached to a predeterminedsupport, a head projection controller using a piezoelectric material isprovided between the support and the arm, and the magnetic head is movedtoward the inside of the rotary cylinder by the head projectioncontroller.

[0032] When the piezoelectric material of the head projection controlleris displaced so as to deflect the support, the magnetic head can easilybe moved toward the inside of the rotary cylinder. Also, providing thehead projection controller between the support and arm can prevent thehead projection controller from being damaged upon contact with themagnetic tape.

[0033] Preferably, in the rotary head in accordance with this aspect ofthe present invention, the magnetic head is moved toward the inside ofthe rotary cylinder by a head projection controller using apiezoelectric material. When the piezoelectric material of the headprojection controller is displaced so as to deflect the support, themagnetic head can easily be moved toward the inside of the rotarycylinder.

[0034] Preferably, in each of the rotary heads utilizing a headprojection controller, the voltage value applied to the piezoelectricmaterial of the head projection controller is adjusted according to themagnitude of output of information read out from the magnetic tape bythe magnetic head.

[0035] This aspect of the present invention utilizes a phenomenon thatthe readout output of a magnetic head increases and decreases as thedistance between the magnetic head and a magnetic tape becomes shorterand longer, respectively. When the output of information read out fromthe magnetic tape is high, the magnetic head may be damaged due to thefriction and shock between the magnetic tape and magnetic head. In sucha case, the voltage value applied to the piezoelectric material israised so as to increase the amount of displacement of the magnetichead, whereby the magnetic head moves away from the magnetic head andthus can be prevented from being damaged.

[0036] In the rotary head in accordance with this aspect of the presentinvention, the magnetic head may include a magnetoresistive device forreading information of the magnetic tape by using a magnetoresistiveeffect.

[0037] When the magnetoresistive device is worn, the depth (so-called MRheight) of the device from its surface opposed to the magnetic tapechanges as mentioned above, thereby altering a characteristic of themagnetic head. Therefore, even when a force directed to the rotarycylinder is applied to the magnetic tape, the magnetic head is movedtoward the inside of the rotary cylinder in this aspect of the presentinvention, whereby the magnetoresistive device is prevented fromreceiving too much shock from or friction with the magnetic tape, andthe magnetic head can be kept from deteriorating its readoutcharacteristic.

[0038] The magnetic head may be an inductive magnetic head. Though theinductive magnetic head is supposed to have a surface to be worn byfriction with a magnetic tape in general in such a configuration, it ismade movable toward the inside of the rotary cylinder, whereby it can beprevented from receiving too much shock from or friction with themagnetic tape.

[0039] The present invention provides a magnetic recording/reproducingapparatus comprising any of the above-mentioned rotary heads, and atransport mechanism for transporting a magnetic tape about the rotaryhead. Since the rotary head is configured such that the contact statebetween the magnetic head and magnetic tape is appropriately regulatedas mentioned above, the magnetic recording/reproducing apparatusequipped with the rotary head is suitable for high-density recording andhigh transfer rate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention may be more readily described withreference to the accompanying drawings, in which:

[0041]FIG. 1 is a schematic view of an embodiment of the magneticrecording/reproducing apparatus in accordance with the presentinvention;

[0042]FIG. 2 is a perspective view of a first embodiment of the rotaryhead in accordance with the present invention;

[0043]FIG. 3 is a view of the rotary head taken in the direction III-IIIof FIG. 2;

[0044]FIG. 4 is a side view of an MR head and its vicinity in the rotaryhead shown in FIG. 2;

[0045]FIG. 5 is an enlarged view of the MR head and its vicinity;

[0046]FIG. 6 is an enlarged view of the MR head and its vicinity;

[0047]FIG. 7 is a perspective view of a second embodiment of the rotaryhead in accordance with the present invention;

[0048]FIG. 8 is a view of the rotary head taken in the directionVIII-VIII of FIG. 7;

[0049]FIG. 9 is a plan view of a support in the rotary head shown inFIG. 7;

[0050]FIG. 10 is an enlarged view of an MR head and its vicinity;

[0051]FIG. 11 is a plan view of a support in a modified example of thesecond embodiment of the rotary head in accordance with the presentinvention;

[0052]FIG. 12 is an enlarged view of an MR head and its vicinity;

[0053]FIG. 13 is a view for explaining a modified example of the secondembodiment of the rotary head in accordance with the present invention;

[0054]FIG. 14 is a perspective view of a third embodiment of the rotaryhead in accordance with the present invention;

[0055]FIG. 15 is a view of the rotary head taken in the direction XV-XVof FIG. 14;

[0056]FIG. 16 is an enlarged view of an MR head and its vicinity;

[0057]FIG. 17 is a schematic view showing a fourth embodiment of therotary head in accordance with the present invention;

[0058]FIG. 18 is a schematic view showing the state where a headprojection controller of the rotary head shown in FIG. 17 is displaced;and

[0059]FIG. 19 is a schematic view showing a modified example of therotary head shown in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] In the following, with reference to the accompanying drawings,preferred embodiments of the rotary head and magneticrecording/reproducing apparatus in accordance with the present inventionwill be explained in detail. Here, constituents identical to each otherwill be referred to with numerals identical to each other withoutrepeating their overlapping explanations.

[0061] First Embodiment

[0062]FIG. 1 is a schematic view showing a magneticrecording/reproducing apparatus 1 in accordance with a first embodiment.The magnetic recording/reproducing apparatus 1 carries out recording orreading of information on a magnetic tape 11 acting as a recordingmedium. Examples of the magnetic recording/reproducing apparatus 1include data storage devices for server backup, Handycam cameras, videodecks, and audio decks. The magnetic recording/reproducing apparatus 1comprises a rotary head 10 mounted with a plurality of magnetic heads 20a to 20 d; a transport mechanism 60 for transporting the magnetic tape11 about the rotary head 10; and a controller 70 for supervisingoperations of the whole apparatus.

[0063] The transport mechanism 60 comprises, successively from theupstream side in the traveling direction of the magnetic tape 11; a feedreel 61 for supplying the magnetic tape 11 toward the rotary head 10; aguide roller 62; guide rollers 63, 64 disposed at positions where themagnetic tape 11 is wound about the rotary head 10; a guide roller 65;and a take-up reel 66 for taking up the magnetic tape 11.

[0064] The controller 70 executes various known functions carried out inthe magnetic recording/reproducing apparatus 1 in addition to adjustingthe timing between the driving of each roller in the transport mechanism60 and the rotation of the rotary head 10, ordering the magnetic headsof the rotary head 10 to record and read information, andsignal-processing the information read out by the magnetic head.

[0065]FIG. 2 is a perspective view of the rotary head 10. The rotaryhead 10 is adapted to so-called helical scanning. The rotary head 10mainly comprises a tubular rotary cylinder 12; a stationary cylinder 14positioned coaxially there under; and a driving motor 16, disposedwithin the stationary cylinder 14, for rotating the rotary cylinder 12.Though this embodiment relates to a rotary head of a type in which therotary cylinder 12 is positioned on the stationary cylinder 14, the formof each cylinder is not restricted thereto.

[0066] At the time of recording/reproducing information with respect tothe magnetic tape 11, the stationary cylinder 14 is kept still withoutrotating. A tape guide 15 defined by a step is formed about thestationary cylinder 14. At the time of recording/reproducing, themagnetic tape 11 travels along the tape guide 15 in the direction ofarrow A in the drawing. Here, the rotary cylinder 12 is rotated at apredetermined rotational speed by the driving motor 16 in the directionof arrow B.

[0067] Referring to FIGS. 3 and 4, the rotary head 10 will now beexplained in more detail. FIG. 3 is a view of the rotary cylinder 12taken in the direction III-III of FIG. 2, whereas FIG. 4 is an enlargedview of one magnetic head 20 a provided in the rotary head 10 and itsvicinity. The rotary head 10 is provided with two write-only inductivemagnetic heads 20 b, 20 d and two read-only magnetoresistive magneticheads (hereinafter also referred to as “MR heads”) 20 a, 20 c which arealternately disposed along its circumference, though the arrangement ofthe magnetic heads 20 a to 20 d is not restricted thereto. The magneticheads 20 a to 20 d are attached to their corresponding supports 22 eachhaving a substantially rectangular parallelepiped shape formed fromAlTiC (Al₂O₃.TiC), for example.

[0068] Employable as the inductive magnetic heads 20 b, 20 d are knownones, e.g., those comprising a pair of magnetic poles sandwiching amagnetic gap therebetween and a copper coil wound thereabout. When ahigh-frequency current is caused to flow through the coil, so as togenerate a magnetic field, information can be recorded on the magnetictape 11. The inductive magnetic heads 20 b, 20 d are attached to theirsupports 22 such that their information recording surfaces are opposedto the magnetic tape 11 being transported.

[0069] The MR heads 20 a, 20 c utilize a so-called magnetoresistiveeffect. Specifically, they include AMR (Anisotropic MagnetoResistive)devices utilizing an anisotropic magnetoresistive effect, GMR (GiantMagnetoResistive) devices utilizing a giant magnetoresistive effect, TMR(Tunnel-type MagnetoResistive) devices utilizing a magnetoresistiveeffect occurring in a tunnel junction, and the like. An MR head canreproduce information at a sensitivity higher than that of an inductivemagnetic head. The MR heads 20 a, 20 c are attached to their supports 22such that their information recording surfaces are opposed to themagnetic tape 11 being transported.

[0070] Though not depicted, the rotary head 10 is provided with wiresfor transmitting recording information to the inductive magnetic heads20 b, 20 d, and wires for transmitting the information read out by theMR heads 20 a, 20 c. These wires may be connected to the controller 70shown in FIG. 1 or to a controller or the like separately providedwithin the stationary cylinder 14.

[0071] Each of the supports 22 having their corresponding magnetic heads20 a to 20 d attached thereto is provided on one end side of an arm 30disposed within the rotary cylinder 12. The arm 30 is axially supportedat its center part by a swing shaft 31, which vertically rises from thebottom face of the rotary cylinder 12, so as to be swingable about theswing shaft 31. As a consequence, the magnetic heads 20 a to 20 d aresupported so as to be movable toward the inside or outside of the rotarycylinder 12.

[0072] The rim of the rotary cylinder 12 is formed with four openings 24at intervals of 90 degrees, whereby the magnetic heads 20 a to 20 d canface the magnetic tape 11 through the respective openings 24. Thougheach opening 24 is formed like a cutout, it may be a hole penetratingthrough the circumference of the rotary cylinder 12.

[0073] Openings 26 are formed at respective positions ahead of theircorresponding openings 24 (magnetic heads 20 a to 20 d) in the rotatingdirection of the rotary cylinder 12. Through the openings 26, airflowsgenerated by the rotation of the rotary cylinder 12 are led into therotary cylinder 12. The openings 26 are set at positions where theairflows led into the rotary cylinder 12 through the openings 26 act onthe arms 30 on their other end side.

[0074] Operations of the rotary head and magnetic recording/reproducingapparatus in accordance with this embodiment will now be explained. Thecase wherein formation is reproduced by the magneticrecording/reproducing apparatus will be represented by way of example.In response to an order to reproduce, the controller 70 starts rotatingthe feed reel 61, the take-up reel 66, and the rotary cylinder 12 of therotary head 10. When the rotary cylinder 12 is stopped, in each of themagnetic heads 20 a to 20 d, the support 22 and magnetic head 20 a to 20d do not project from the outer peripheral face of the rotary cylinder12 as shown in FIG. 5. When the controller 70 starts rotating the rotarycylinder 12, an airflow F led into the rotary cylinder 12 through theopening 26 occurs as shown in FIG. 6 due to the rotation of the rotarycylinder 12. This airflow F swings the arm 30 in the direction of arrowC, thereby moving the support 22 and magnetic head 20 a to 20 d towardthe outside of the rotary cylinder 12 (see FIG. 6).

[0075] Since the magnetic heads 20 a to 20 d are supported so as to bemovable toward the outside of the rotary cylinder 12 as in theforegoing, this embodiment can appropriately regulate the contact statebetween the magnetic heads 20 a to 20 d and the magnetic tape 11.

[0076] The magnetic heads 20 a to 20 d are swingably supported by therespective arms 30 disposed within the rotary cylinder 12. Since thearms 30 swingably supporting the magnetic heads 20 a to 20 d areprovided as such, the magnetic heads 20 a to 20 d can easily be movedtoward the outside of the rotary cylinder 12.

[0077] Each of the magnetic heads 20 a to 20 d is disposed on one endside of its corresponding arm 30, and is moved toward the outside of therotary cylinder 12 when an airflow generated by the rotation of therotary cylinder 12 acts on the other end side of the arm 30. As aconsequence, a configuration which can move the magnetic heads 20 a to20 d toward the outside of the rotary cylinder 12 can be realized simplyat a low cost.

[0078] The rotary cylinder 12 is formed with the openings 26, disposedat positions ahead of their corresponding former openings 24 (magneticheads 20 a to 20 d) in the rotating direction of the rotary cylinder 12,for leading the above-mentioned airflow to the inside. As a consequence,the airflow generated by the rotation of the rotary cylinder 12 canreliably be led into the rotary cylinder 12, so as to act on the otherend side of the arms 30.

[0079] In particular, modifying the shape of openings 26 changes themagnitude of airflow led into the rotary cylinder 12, thereby alteringthe force acting on the other end side of the arms 30. When the form ofopenings 26 is set appropriately as such, the contact state between themagnetic heads 20 a to 20 d and the magnetic tape 11 can be adjustedmore suitably.

[0080] As mentioned above, the rotary head 10 utilizes the MR heads 20a, 20 c as magnetic heads for reproduction. The MR heads areadvantageous in that their sensitivity is higher than that of inductivemagnetic heads. However, it is unfavorable for the MR heads to havetheir surfaces worn by friction with a magnetic tape like the inductivemagnetic heads. If a magnetoresistive device is worn in particular, thedepth (so-called MR height) of the device from its surface opposed tothe magnetic tape will change, thereby altering characteristics of themagnetic head. If the magnetic head and the magnetic tape are separatedfrom each other, the output sensitivity will decrease greatly, therebydeteriorating the output characteristic. Namely, it is more importantfor the MR heads than the inductive magnetic heads to adjust theircontact state with respect to the magnetic tape appropriately.Therefore, this embodiment is effective in the inductive magnetic heads20 b, 20 d and more in the MR heads 20 a, 20 c. That is, this embodimentcan appropriately adjust the contact state between the MR heads 20 a, 20c and the magnetic tape 11, thereby preventing the MR heads 20 a, 20 cfrom receiving too much shock or friction while keeping them fromdeteriorating their output characteristics.

[0081] Second Embodiment

[0082] With reference to FIGS. 7 to 10, a second embodiment of thepresent invention will now be explained. As for the magneticrecording/reproducing apparatus, one similar to that of FIG. 1 can beemployed.

[0083]FIG. 7 is a perspective view of a rotary head 10 in accordancewith this embodiment. FIG. 8 is a view of a rotary cylinder 12 taken inthe direction VIII-VIII of FIG. 7. Magnetic heads 20 a to 20 d areattached to their corresponding supports 40 each having a substantiallyrectangular parallelepiped shape formed from AlTiC (Al₂O₃.TiC), forexample. The supports 40 having the respective magnetic heads 20 a to 20d attached thereto are secured to their corresponding support members 41disposed within the rotary cylinder 12. Each support member 41 issecured at its center part to a shaft 42 vertically rising from thebottom face of the rotary cylinder 12. As a consequence, the magneticheads 20 a to 20 d themselves are kept from moving toward the inside oroutside of the rotary cylinder 12.

[0084] Each support 40 is formed with grooves 40 a at its surfaceopposed to the magnetic tape 11 such that a negative pressure (statewith a pressure lower than the atmospheric pressure) is generatedbetween the surface opposed to the magnetic tape 11 and the magnetictape 11 by an airflow caused by the traveling of the magnetic tape 11and the rotation of the rotary cylinder 12 (see FIG. 9). The grooves 40a function as gap adjusting means for adjusting the gap between themagnetic heads 20 a to 20 d and the magnetic tape 11 by using airflowsgenerated between the magnetic heads 20 a to 20 d and the magnetic tape11.

[0085] Operations of the rotary head and magnetic recording/reproducingapparatus in accordance with this embodiment will now be explained. Thecase where information is reproduced by the magneticrecording/reproducing apparatus will be represented by way of example.In response to an order to reproduce, the controller 70 starts rotatingthe feed reel 61, the take-up reel 66, and the rotary cylinder 12 of therotary head 10. Then, the traveling of the magnetic tape 11 and therotation of the rotary cylinder 12 generate an airflow therebetween,there by yielding a negative pressure state between the surface ofsupport 40 opposed to the magnetic tape 11 and the magnetic tape 11.Thus generated negative pressure acts on the magnetic tape 11, therebymoving the magnetic tape 11 toward magnetic heads 20 a to 20 d (in thedirection of arrow D) as shown in FIG. 10. This adjusts the gap betweenthe magnetic heads 20 a to 20 d and the magnetic tape 11.

[0086] Since the surface of support 40 opposed to the magnetic tape 11is formed with the grooves 40 a such that the airflow caused by thetraveling of the magnetic tape 11 and the rotation of the rotarycylinder 12 generates a negative pressure between the surface opposed tothe magnetic tape 11 and the magnetic tape 11, this embodiment canadjust the contact state between the magnetic heads 20 a to 20 d and themagnetic tape 11 in a direction in which the magnetic tape 11 approachesthe magnetic heads 20 a to 20 d. Since the grooves 40 a adjust the gapbetween the magnetic heads 20 a to 20 d and the magnetic tape 11 assuch, the contact state between the magnetic heads 20 a to 20 d and themagnetic tape 11 can be regulated appropriately.

[0087] In particular, modifying the shape of grooves 40 a changes themagnitude of airflow generated by the traveling of the magnetic tape 11and the rotation of the rotary cylinder 12, thereby altering themagnitude of negative pressure occurring between the surface opposed tothe magnetic tape 11 and the magnetic tape 11. When the form of grooves40 a is set appropriately as such, the contact state between themagnetic heads 20 a to 20 d and the magnetic tape 11 can be adjustedmore suitably.

[0088] With reference to FIGS. 11 and 12, a modified example of thisembodiment will now be explained. This example differs from the modeshown in FIGS. 7 to 10 in the shape of grooves formed in the support 40.

[0089] In this example, grooves 40 b are formed in the surface opposedto the magnetic tape 11 such that an airflow caused by the traveling ofthe magnetic tape 11 and the rotation of the rotary cylinder 12generates a positive pressure (state with a pressure higher than theatmospheric pressure) between the surface opposed to the magnetic tape11 and the magnetic tape 11 (see FIG. 11). As with the grooves 40 a, thegrooves 40 b function as gap adjusting means for adjusting the gapbetween the magnetic heads 20 a to 20 d and the magnetic tape 11 byusing the airflow generated between the magnetic heads 20 a to 20 d andthe magnetic tape 11.

[0090] Operations of the rotary head and magnetic recording/reproducingapparatus in this example will now be explained. The case whereinformation is reproduced by the magnetic recording/reproducingapparatus will be represented by way of example. In response to an orderto reproduce, the controller 70 starts rotating the feed reel 61, thetake-up reel 66, and the rotary cylinder 12 of the rotary head 10. Then,the traveling of the magnetic tape 11 and the rotation of the rotarycylinder 12 generate an airflow therebetween, thereby yielding apositive pressure state between the surface of support 40 opposed to themagnetic tape 11 and the magnetic tape 11. Thus generated positivepressure acts on the magnetic tape 11, thereby moving the magnetic tape11 away from the magnetic heads 20 a to 20 d (in the direction of arrowE) as shown in FIG. 12. This adjusts the gap between the magnetic heads20 a to 20 d and the magnetic tape 11.

[0091] Since the surface of support 40 opposed to the magnetic tape 11is formed with the grooves 40 b such that the airflow caused by thetraveling of the magnetic tape 11 and the rotation of the rotarycylinder 12 generates a positive pressure between the surface opposed tothe magnetic tape 11 and the magnetic tape 11, this example can adjustthe contact state between the magnetic heads 20 a to 20 d and themagnetic tape 11 in a direction in which the magnetic tape 11 moves awayfrom the magnetic heads 20 a to 20 d. Since the grooves 40 b adjust thegap between the magnetic heads 20 a to 20 d and the magnetic tape 11 assuch, the contact state between the magnetic heads 20 a to 20 d and themagnetic tape 11 can be regulated appropriately.

[0092] In particular, modifying the shape of grooves 40 b changes themagnitude of airflow generated by the traveling of the magnetic tape 11and the rotation of the rotary cylinder 12, thereby altering themagnitude of positive pressure occurring between the surface opposed tothe magnetic tape 11 and the magnetic tape 11. When the form of grooves40 b is set appropriately as such, the contact state between themagnetic heads 20 a to 20 d and the magnetic tape 11 can be adjustedmore suitably.

[0093]FIG. 13 is a view showing a modified example of the secondembodiment. In this example, unlike FIGS. 8 and 12, support members 41are formed like arms. In this case, each of the magnetic heads 20 a to20 d is attached to one end side of its corresponding support member 41,whereas the other end side of the support member 41 is secured to ashaft 42.

[0094] Third Embodiment

[0095]FIG. 14 is a perspective view of a rotary head 10 in accordancewith a third embodiment. FIG. 15 is a view of a rotary cylinder 12 takenin the direction XV-XV of FIG. 14. FIG. 16 is an enlarged view of onemagnetic head 20 a provided in the rotary head 10 and its vicinity. Therotary head 10 is provided with two inductive magnetic heads 20 b, 20 dand two read-only magnetoresistive magnetic heads 20 a, 20 c which arealternately disposed along its circumference, though the arrangement ofthe magnetic heads 20 a to 20 d is not restricted thereto.

[0096] Supports 22 having the respective magnetic heads 20 a to 20 dattached thereto are supported by their corresponding suspension arms 30made of a stainless steel such as SUS304, for example. The suspensionarms 30 are supported by their corresponding support tables 27 attachedto the inner periphery of the rotary cylinder 12. The suspension arms 30have a flexibility, and support the magnetic heads 20 a to 20 d suchthat the latter are swingable in the directions of arrows F. Morespecifically, the selection of material of suspension arms 30, theirload setting, adjustment of their form of suspension, and the like arecarried out such that the pressure caused by a certain shock receivedfrom the traveling magnetic tape 11 or the airflow caused by thetraveling of the magnetic tape 11 and the rotation of the rotarycylinder 12 moves the magnetic heads 20 a to 20 d toward the inside ofthe rotary cylinder 12. Each support 22 is formed with grooves 22 a atits surface opposed to the magnetic tape 11, so as to make it easier forthe airflow to adjust the contact force between the magnetic heads andthe magnetic tape 11 (see FIG. 16). As such a suspension arm 30, oneutilized in a hard disk apparatus is also employable.

[0097] The rim of the rotary cylinder 12 is formed with four openings 24at intervals of 90 degrees, whereby the magnetic heads 20 a to 20 d canface the magnetic tape 11 through their corresponding openings 24.Though each opening 24 is formed like a cutout, it may be a holepenetrating through the circumference of the rotary cylinder 12.Preferably, the inclination of suspension arms 30 and their suspensionstrength are adjusted such that the information recording surfaces ofthe inductive magnetic heads 20 b, 20 d and the information readingsurfaces of the MR heads 20 a, 20 c project from the outer periphery ofthe rotary cylinder 12 to some extent in a state where no external forceis applied to the arms 30. Then, the magnetic heads 20 a to 20 dprojected from the outer periphery of the rotary cylinder 12 come intocontact with the magnetic tape 11 at least when the rotary cylinder 12is stopped as shown in FIG. 15.

[0098] Operations of the rotary head and magnetic recording/reproducingapparatus in accordance with this embodiment will now be explained. Thecase where information is reproduced by the magneticrecording/reproducing apparatus will be represented by way of example.As the magnetic recording/reproducing apparatus, one shown in FIG. 1 canbe employed. In response to an order to reproduce, the controller 70starts rotating the feed reel 61, the take-up reel 66, and the rotarycylinder 12 of the rotary head 10. Then, the traveling of the magnetictape 11 and the rotation of the rotary cylinder 12 generate an airflowtherebetween. Though the magnetic heads 20 a to 20 d are firmly incontact with the magnetic tape 11 when the rotary cylinder 12 is stopped(see FIG. 15), the above-mentioned airflow moves the supports 22 andmagnetic heads 20 a to 20 d toward the inside of the rotary cylinder 12.Here, each suspension arm 30 is in a state where its leading end sideconnected to the support 22 is flexed away from the magnetic tape 11(toward the center of the rotary cylinder 12 in the direction of one ofarrows F in FIG. 15). Since the suspension arms 30 have a flexibility,the supports 22 can easily be moved toward the inside of the rotarycylinder 12.

[0099] Retracting the magnetic heads 20 a to 20 d toward the inside ofthe rotary cylinder 12 by using the airflow can appropriately regulatethe contact state between the magnetic head and magnetic tape. This canprevent the magnetic heads 20 a to 20 d from receiving too much shockform or friction with the magnetic tape 11. Here, it is not alwaysnecessary for the magnetic heads 20 a to 20 d to retract to the innerspace of the rotary cylinder 12. It will be sufficient if they move tosuch an extent that the contact force with respect to the magnetic tape11 can be lowered. From the viewpoint of carrying out informationrecording by the inductive magnetic heads 20 b, 20 d and informationreading by the MR heads 20 a, 20 c at a high sensitivity, it will bepreferred if the magnetic heads 20 a to 20 d are slightly in contactwith the magnetic tape 11 instead of being completely separated from thelatter.

[0100] The magnetic heads 20 a to 20 d may receive a certain shock fromthe magnetic tape 11 in addition to the above-mentioned airflow. Whenthe supports 22 and magnetic heads 20 a to 20 d receive a shock as such,the suspension arms 30 flex, whereby each magnetic head retracts to theinside of the rotary cylinder. This can alleviate the impact forcereceived by each of the magnetic heads 20 a to 20 d, thereby preventingthe magnetic heads from being damaged.

[0101] As mentioned above, the rotary head 10 utilizes the MR heads 20a, 20 c as reproducing magnetic heads. When the MR heads are worn,so-called MR height changes, thereby altering characteristics of themagnetic heads. Namely, it is more necessary for the MR heads than theinductive magnetic heads to lower their contact force with respect tothe magnetic tape. Therefore, this embodiment is effective in theinductive magnetic heads 20 b, 20 d and more in the MR heads 20 a, 20 c.That is, this embodiment can prevent the MR heads 20 a, 20 c havingsurfaces which are not supposed to be worn from wearing and restraintheir MR height from changing.

[0102] Though this embodiment utilizes suspension arms 30 which arelikely to flex, the configuration for moving the magnetic heads towardthe inside of the rotary cylinder 12 is not restricted thereto. Forexample, a highly rigid arm may be made rotatable about a predeterminedaxis, such that a magnetic head is swingable. Further, magnetic headsand supports may be supported with elastic members such as coil springsor other kinds of springs, instead of arms in a cantilever fashion.Namely, any configuration can be employed as long as a magnetic head issupported so as to be movable toward the inside of the rotary cylinder12 when an external force is applied to a support or the magnetic head.When a configuration in which a magnetic head is swingably supported byan arm in a cantilever fashion as in this embodiment is employed,however, a simple configuration can prevent the magnetic head and themagnetic tape from coming into too much contact with each other.

[0103] Fourth Embodiment

[0104] With reference to FIGS. 17 to 19, a fourth embodiment of thepresent invention will now be explained. This embodiment differs fromthe third embodiment in that a head projection amount controller using apiezoelectric material is utilized in order to move magnetic headstoward the inside of the rotary cylinder 12. As for the magneticrecording/reproducing apparatus, one similar to that of FIG. 1 can beemployed.

[0105]FIG. 17 is an enlarged view of an MR head 20 a and its vicinity inthe rotary head of this embodiment. As depicted, a head projectioncontroller 40 comprising a piezoelectric material is embedded in asupport 22 on the upper face side (on the side of the surface opposed tothe magnetic tape 11) in the drawing. The head projection controller 40is of bimorph type which deflects when a voltage is applied thereto, andis provided with two piezoelectric layers 41, 42 utilizing PZT as apiezoelectric material. As indicated by outlined thick arrows in thedrawing, the polarizing directions of piezoelectric layers 41 and 42 areupward and downward in the drawing, respectively. Here, while PZT refersto ceramics obtained by mixing lead titanate (PbTiO₃) and lead zirconate(PbZrO₃) together, various other known piezoelectric materials can beutilized as well.

[0106] An electrode plate 43 is disposed under the piezoelectric layer41. An electrode plate 44 is disposed between the piezoelectric layers41 and 42. An electrode plate 45 is disposed on the piezoelectric layer42. A power supply 72 within a controller 70 applies voltages to theelectrode plates 43, 44, 45. Namely, a positive voltage is applied tothe topmost electrode plate 45, the center electrode plate 44 isgrounded, and a negative voltage is applied to the bottom electrodeplate 43.

[0107] The controller 70 incorporates therein a readout informationprocessor 74 for processing the information of magnetic tape read out bythe MR head 20 a, whereas the MR head 20 a and the readout informationprocessor 74 are connected to each other by a wire. A CPU 76 supervisesthe processing of the controller 70, and is set so as to actuate thepower supply 72 when the magnitude of information read out by thereadout information processor 74 exceeds a predetermined referencevalue, thereby applying voltages to the head projection controller 40.The reference value maybe stored in the CPU 76, the readout informationprocessor 74, or other memories.

[0108] Operations of the rotary head and magnetic recording/reproducingapparatus in this embodiment will now be explained. If the contact forcebetween a magnetic tape and the MR head 20 a is too strong during whenthe MR head 20 a reads out information of the magnetic tape, the readoutinformation processor 74 may determine that the magnitude of readoutinformation in the MR head 20 a exceeds a predetermined reference value.In such a case, the CPU 76 actuates the power supply 72, so as to applya positive voltage to the electrode plate 45, ground the electrode plate44, and apply a negative voltage to the electrode plate 43.

[0109] When voltages are applied to the electrode plates 43 to 45 assuch, their relationships with the polarizing directions cause the upperpiezoelectric layer 42 and the lower piezoelectric layer 41 to expandand shrink sidewise in the drawing, respectively, as shown in FIG. 18.As a result, a support 22 (indicated by broken lines for convenience ofexplanation) deflects as indicated by arrow G, there by moving the MRhead 20 a toward the inside of the rotary cylinder, i.e., away from themagnetic tape. Then, by constantly keeping the distance or load from themagnetic tape 11, the MR head 20 a can be prevented from being damaged.

[0110] Though this embodiment is configured such that the piezoelectriclayers 41, 42 of the head projection controller 40 are displaced whenthe output value of an MR head exceeds a predetermined reference value,voltage values applied to the head projection controller 40 may beadjusted in proportion to the output value of the MR head. Though an MRhead is explained hereby way of example, inductive magnetic heads forrecording can also be moved by displacement of a head projectioncontroller. When utilizing the head projection controller 40, suspensionarms are not always necessary. In this case, it will be sufficient ifthe magnetic heads 20 a to 20 d are supported so as to be movable towardthe inside of the rotary cylinder upon displacement of the headprojection controller 40.

[0111] With reference to FIG. 19, a modified example of this embodimentwill now be explained. This example differs from the mode shown in FIG.17 in the location where the head projection controller 40 is placed. Inthis example, the head projection controller 40 is disposed between thesupport 22 and the suspension arm 30. The displacement of headprojection controller 40 shown in FIG. 18 can move the magnetic heads 20a to 20 d toward the inside of the rotary cylinder in the case employingsuch a configuration as well. This can reduce damages of the magneticheads which may occur upon too much contact with the magnetic tape.Further, since the head projection controller 40 is disposed between thesupport 22 and suspension arm 30, this example can prevent the headprojection controller 40 from being damaged upon contact with themagnetic tape.

[0112] The fourth embodiment uses the piezoelectric material of the headprojection controller 40 as means for converting electric energy tomechanical energy. On the other hand, the piezoelectric materialgenerates a voltage when a stress is applied thereto, thus functioningto convert mechanical energy to electric energy. Utilizing the latterconverting function, the head projection controller 40 may be arrangedin contact with the magnetic tape 11, so that the contact pressure withrespect to the magnetic tape 11 can be measured directly. When the armsupporting the magnetic head is moved toward the inside of the rotarycylinder according to thus measured contact pressure, the magnetic headcan be restrained from being damaged.

[0113] In this case, a first piezoelectric member for measuring thecontact pressure may be provided on the side of the surface of support22 opposed to the magnetic head 11, whereas a second piezoelectricmember for moving the magnetic head may be disposed on the opposite side(suspension arm side). In this case, the piezoelectric members canrealize operations from the measurement of contact pressure to themovement of magnetic head.

[0114] Though the invention achieved by the inventors is specificallyexplained with reference to embodiments in the foregoing, the inventionis not restricted to the above-mentioned embodiments. For example, themagnetic head provided in the rotary head may be a combination head inwhich a reproducing MR head and a recording inductive magnetic head areintegrated.

[0115] Also, the surface of support 22 opposed to the magnetic tape 11in the first embodiment may be formed with the grooves 40 a, 40 b in thesecond embodiment.

[0116] As explained in the foregoing, the present invention can providea rotary head which can appropriately adjust the contact state between amagnetic head and a magnetic tape, and a magnetic recording/reproducingapparatus equipped therewith.

[0117] The basic Japanese Applications No. 2002-54126 filed on Feb. 28,2002 and No. 2002-148115 filed on May 22, 2002 are hereby incorporatedby reference.

What is claimed is:
 1. A rotary head comprising: a tubular rotary cylinder; and a magnetic head for carrying out at least one of recording and reading of information with respect to a magnetic tape transported about said rotary cylinder; wherein said magnetic head is supported so as to be movable toward the outside of said rotary cylinder.
 2. A rotary head according to claim 1, wherein said magnetic head is swingably supported by an arm disposed within said rotary cylinder.
 3. A rotary head according to claim 1, wherein said magnetic head is disposed on one end side of said arm; and wherein said magnetic head moves toward the outside of said rotary cylinder when an airflow caused by a rotation of said rotary cylinder acts on the other end side of said arm.
 4. A rotary head according to claim 3, wherein said rotary cylinder is formed with an opening, disposed at a position ahead of said magnetic head in the rotating direction of said rotary cylinder, for introducing said airflow therein.
 5. A rotary head according to claim 1, wherein said magnetic head includes a magnetoresistive device for reading information of said magnetic tape by using a magnetoresistive effect.
 6. A rotary head according to claim 1, wherein said magnetic head is an inductive magnetic head.
 7. A magnetic recording/reproducing apparatus comprising the rotary head according to claim 1, and a transport mechanism for transporting a magnetic tape about said rotary head.
 8. A rotary head comprising: a tubular rotary cylinder; a magnetic head for carrying out at least one of recording and reading of information with respect to a magnetic tape transported about said rotary cylinder; and gap adjusting means for adjusting a gap between said magnetic head and said magnetic tape by using an airflow generated between said magnetic head and said magnetic tape.
 9. A rotary head according to claim 8, wherein said gap adjusting means includes a groove formed in a support for attaching said magnetic head thereto at a surface opposed to said magnetic tape, and generates a positive pressure between said magnetic tape and said surface opposed to said magnetic tape.
 10. A rotary head according to claim 8, wherein said gap adjusting means includes a groove formed in a support for attaching said magnetic head thereto at a surface opposed to said magnetic tape, and generates a negative pressure between said magnetic tape and said surface opposed to said magnetic tape.
 11. A rotary head according to claim 8, wherein said magnetic head includes a magnetoresistive device for reading information of said magnetic tape by using a magnetoresistive effect.
 12. A rotary head according to claim 8, wherein said magnetic head is an inductive magnetic head.
 13. A magnetic recording/reproducing apparatus comprising the rotary head according to claim 8, and a transport mechanism for transporting a magnetic tape about said rotary head.
 14. A rotary head comprising: a tubular rotary cylinder; and a magnetic head for carrying out at least one of recording and reading of information with respect to a magnetic tape transported about said rotary cylinder; wherein said magnetic head is supported so as to be movable toward the inside of said rotary cylinder.
 15. A rotary head according to claim 14, wherein said magnetic head is moved toward the inside of said rotary cylinder by a pressure from said magnetic tape.
 16. A rotary head according to claim 14, wherein said magnetic head is moved toward the inside of said rotary cylinder by an airflow generated between said magnetic head and said magnetic tape.
 17. A rotary head according to claim 14, wherein said magnetic head is swingably supported by an arm disposed within said rotary cylinder.
 18. A rotary head according to claim 17, wherein said rotary cylinder is formed with an opening; and wherein at least a part of said magnetic head projects to a periphery of said rotary cylinder from said opening.
 19. A rotary head according to claim 17, wherein said arm has a flexibility.
 20. A rotary head according to claim 17, wherein said magnetic head is attached to a predetermined support; wherein a surface opposed to said magnetic tape in said support is provided with a head projection controller using a piezoelectric material; and wherein said magnetic head is moved toward the inside of said rotary cylinder by said head projection controller.
 21. A rotary head according to claim 17, wherein said magnetic head is attached to a predetermined support; wherein a head projection controller using a piezoelectric material is provided between said support and said arm; and wherein said magnetic head is moved toward the inside of said rotary cylinder by said head projection controller.
 22. A rotary head according to claim 20, wherein a voltage value applied to said piezoelectric material of said head projection controller is adjusted according to the magnitude of output of information readout from said magnetic tape by said magnetic head.
 23. A rotary head according to claim 14, wherein said magnetic head is moved toward the inside of said rotary cylinder by a head projection controller using a piezoelectric material.
 24. A rotary head according to claim 23, wherein a voltage value applied to said piezoelectric material of said head projection controller is adjusted according to the magnitude of output of information read out from said magnetic tape by said magnetic head.
 25. A rotary head according to claim 14, wherein said magnetic head includes a magnetoresistive device for reading information of said magnetic tape by using a magnetoresistive effect.
 26. A rotary head according to claim 14, wherein said magnetic head is an inductive magnetic head.
 27. A magnetic recording/reproducing apparatus comprising the rotary head according to claim 14, and a transport mechanism for transporting a magnetic tape about said rotary head. 